(i) In semi-arid regions of Rajasthan every house had underground tankas to store the water for drinking purposes.(ii) These tankas are large and deep which were built inside the main house or the courtyard.(iii) They were linked to the sloping roofs of the houses through a pipe. Rainwater falling on the rooftops would run down through a pipe and collect in the underground tankas.(iv) The rainwater collected, is stored in the tankas providing drinking water till the next rainy season.(v) When all other sources have dried up, these tankas were beneficial to beat the summer heat as they kept the rooms cool. The rainwater or palar pani, as commonly known in these parts, is considered the purest form of natural water.